Impacts: Currently, the United States is in the midst of an opioid use disorder (OUD) epidemic with the rates of emergency room visits and overdoses related to prescription opioids skyrocketing and the rates of heroin use increasing rapidly. OUD is associated with increased morbidity and mortality, increased HIV and HCV infection rates, and increased criminal behavior. Opioid agonist therapy (OAT) has been shown to be effective in treating OUD and decreasing these negative consequences. While the efficacy of OAT has been established, the predominant problem is that of implementation: too few providers offer or provide OAT to patients with OUD due to patient, provider or system impediments. While the VHA has made great strides in implementation of OAT over the past decade, national treatment rates remain low (30% of those Veterans eligible to receive OAT do) and several facilities continue to have very low prescribing rates. Background: OAT using methadone or buprenorphine is the most effective treatment available for OUD. While methadone prescribing must take place in highly regulated opioid treatment centers, buprenorphine may be prescribed in non-addiction treatment settings allowing for easier access for patients. When agonist treatment is contraindicated or not acceptable to the patient, antagonist medication (naltrexone) could be considered. Objectives: The objective of this study is to increase the percentage of Veterans with OUD initiating and sustaining OAT in long-term treatment (a minimum of 3 months) in facilities where the current percent of Veterans receiving medication for OUD is low (<15%). This project will not focus on establishing new methadone opioid treatment centers, but rather focus on using intensive external facilitation to increase access to buprenorphine and (in cases where buprenorphine is contraindicated or not acceptable to the patient) naltrexone prescribing. This objective will be accomplished by: 1) implementing intensive external facilitation at 8 low-performing sites and comparing the change in rate of OAT initiation and sustainment to the remaining low performing sites, 2) using formative evaluation methods to refine the intervention for further dissemination, and 3) assessing the cost and budget impact of the intervention. Methods: Eight sites will be selected based on prescribing rates and number of actionable patients (e.g., patients with OUD not currently receiving OAT) to receive the intervention. Remaining low-performing sites will continue to receive implementation as usual (e.g., MHS/OMHO and Academic Detailing interventions). Administrative data will be used to monitor the proportion of Veterans with OUD initiating and sustaining OAT at all low-performing sites. The intervention will include a site-specific developmental evaluation, a kick-off site visit and 12 months of ongoing facilitation. The developmental evaluation will consist of qualitative interviews with patients, substance use disorders clinic staff, and primary care and general mental health leadership to assess site level barriers. The site visit will include: 1) a review of site-specific barriers and potential implementation strategies; 2) instruction on using already available dashboards to track prescribing rates and identify actionable patients; and 3) education on OAT, including required education to obtain waivers for buprenorphine prescribing. On-going facilitation will consist of monthly conference calls with individual site teams and expert clinical consultation available via video conferencing. The primary outcomes will be the proportion of Veterans with a diagnosis of OUD initiating and sustaining OAT. Because implementation of OAT is a current focus of MHS/OMHO and the Academic Detailing Program, the percentage of Veterans with OUD initiating and sustaining OAT is expected to increase at all sites but the increase in the intervention sites is predicted to be significantly greater. Final qualitative interviews and a cost assessment will inform quantitative results.